Abstract: Objective To investigate the effect of daily mean temperature on the daily incidence of hand, foot, and mouth disease (HFMD) in the north-central region of Shenzhen and to analyze the differential effects among various age groups. Methods Data on HFMD incidence and meteorological records from 2010 to 2023 were collected for the north-central districts of Shenzhen (Longgang and Longhua). A Distributed Lag Non-linear Model (DLNM) was employed to analyze the impact of temperature and lag days on HFMD incidence, using 24.6 ℃ (P₅₀) as the reference. The single-day and cumulative lag effects of low temperature (P₅=13.5 ℃) and high temperature (P₉₅=30.0 ℃) were subsequently explored. Results A total of 250 138 HFMD cases were reported in north-central Shenzhen between 2010 and 2023, corresponding to an average annual incidence rate of 336.98 per 100 000 population. The overall temperature-HFMD association, cumulative over a 21-day lag, exhibited an inverted "V" shape, with the peak relative risk (RR) of 3.567 (95% CI: 3.279-3.880) occurring at 28.7 °C. Low temperatures were associated with an increased risk of incidence at lags of 1-3 days, whereas high temperatures demonstrated an increased risk across lags of 1-21 days (RR>1). The cumulative lag effect of low temperature was found to be protective (RR<1), while that of high temperature was detrimental (RR>1). The effects of both low and high temperatures were more pronounced in children under the age of five. Conclusions The relationship between daily mean temperature and the daily incidence of HFMD in north-central Shenzhen is non-linear and subject to a lag effect. Enhanced prevention and control measures are warranted during periods of high temperature, with a specific focus on children under five years of age. Conversely, during periods of low temperature, attention should be directed towards the population aged five years and older.

Key words: Hand,foot,and mouth disease, Daily mean temperature, Distributed lag non-linear model, Age